1. Field of the Invention
The present invention relates to an automatic musical composition classification device and method for automatically classifying a plurality of musical compositions.
2. Description of the Related Art
Due to the popularization of compressed musical data and the increased capacities of storage devices in recent years, individuals have also been able to store and enjoy large amounts of music. On the other hand, it has become extremely difficult for users to sort large quantities of musical compositions and find the musical composition that they would like to listen to. There is therefore a need for an effective musical composition classification and selection method to resolve this problem.
Conventional musical composition classification methods include methods that use information appearing in a bibliography such as the song title, singer, the name of the genre to which the music belongs such as rock or popular music, and the tempo in order to classify musical compositions stored in large quantities as specific kinds of music, as disclosed in Japanese Patent Kokai No. 2001-297093.
Methods also include a method used in classification and selection that allocates a word or expression such as ‘uplifting’ that can be shared between a multiplicity of subjects who listen to the music for characteristic amounts such as beat and frequency fluctuations that are extracted from a musical composition signal, as disclosed by Japanese Patent Kokai No. 2002-278547.
Furthermore, a method has been proposed that extracts three musical elements (melody, rhythm, and harmony) from part of a musical composition signal such as rock or ‘enka’ (modern Japanese ballad) and associates these three elements with a genre identifier such that, when a source of music with a mix of genres and the name of the object genre are subsequently provided, only the music source matching the genre name is recorded in a separate device, as disclosed by Japanese Patent Application Laid Open No. 2000-268541.
Further, a known conventional musical composition classification method performs automatic classification in the form of a matrix by using, as musical characteristic amounts, the tempo, major or minor keys, and soprano and base levels, and then facilitates selection of the musical composition, as disclosed by Japanese Patent Kokai No. 2003-58147.
There are also methods that extract acoustic parameters (cepstrum and power higher order moments) of music that has been selected once by the user and then subsequently present music with similar acoustic parameters, as disclosed by Japanese Patent Kokai No. 2002-41059.
However, the method of using information displayed in a bibliography such as the song title, genre, and so forth illustrated in Japanese Patent Kokai No. 2001-297093 has been confronted by problems, i.e. this method requires work on the part of the individual, does not permit a network connection, and does not function at all when information for classification is hard to obtain. For example, this method does not function at all when information for classification is hard to obtain.
In the case of the classification method of Japanese Patent Kokai No. 2002-278547, a listener's image of the music is subjective and, because this image is vague and varies even for the same listener, continuous results cannot be expected when classification is performed using an image other than that of the party concerned. Therefore, in order to retain the effect of subjective image language, continuous feedback from the listener for the classification operation is required, which makes for problems such as that of forcing a labor-intensive operation on the listener. There is also the problem that the classification of beat or other rhythm information is limited by the target music.
According to the classification method of Japanese Patent Kokai No. 2000-268541, classification takes place by using at least one of three musical elements extracted from the musical composition signal. However, the specific association between each characteristic amount and genre identifier is difficult based on the disclosed technology. Further, it is hard to consider a large classification key for determining the genre in classification that uses only a few bars' worth of the three musical elements.
The proposed combination of the tempo and tonality, and so forth, of the classification method of Japanese Patent Kokai No. 2003-58147 allows the clarity and pace of the music to be implemented fundamentally and is desirable in order to express the melody. The words “melody” and “melodies” that we referred here and hereafter do not represent specific elements like vocal or instrumental parts of music. Rather these words are intended to represent a rough tune of music, like similarities of accompaniments or arrangements of music. In the classification method described above, there is however a problem that the tempo, tonality and so forth of the actual musical composition have very little consistency and accuracy is low for characteristic amounts that allow classification to be performed in musical composition units.
Further, with the methods of Japanese Patent Kokai Nos. 2001-297093, 2002-278547, 2000-268541, and 2003-58147, music selections are made by using statically defined language such as image words, genre names, and major and minor keys, and because the impression of the musical composition varies depending on the mood, there is the problem that the appropriate music composition selection cannot be made.
Although Japanese Patent Kokai No. 2002-41059 describes the fact that musical compositions matched to the listener's preferences are provided as musical compositions are selected, because the characteristic amounts that are actually used are rendered by converting results extracted from all or part of the music signal into numerical values, variations in the melody in the musical composition cannot be expressed. The problem therefore exists that the precision that is appropriate for classifying musical compositions based on preferences cannot be secured.